Telephone system.



G. DEAKIN.

TELEPHONE SYSTEM.

APPLICATION mw MAY sa, m2.

Patented Dec. 25. 1917.

3 SHEEYS-SHEEI l.

5mi/55M UEEEES:

G. DEAKIN.

TELEPHONE SYSTEM.

APPLICATION man MAY4'3.19|2.

Patented Dec. '25, 1917 In; a sains-skier z..-

JJUPHET:

G. DEAKIN.

TELEPHONE SYSTEM.

APPLICATION man nula. 1912.

1,251,350. 4 Patented Dc. 25,1917.

3 SHEETS--SHEET 3.

@if e m .72-7UE UTEP.'

, i My invention relates to te 'UNITED STATES PATENT OFFICE;

GERALD DEAKI, 0F SAN FRANCISCO, CALIFORNLA. ASSIGNOB TO KELLOGG SWITCH- BOARD SUPPLY COMPANY, 0F CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

TELEPHONE SYSTEM.

To all whom it may concern:

Be it known that I, GERALD DEAKIN, a citizen of the United States, residing at San Francisco, county of San Francisco7 State of California, have invented certain new and useful Improvements in Telephone Systems, of which the following is a specification.

a nd more particularly to automatic telephone systems or systems in which automatic switches are iused for interchangeably connecting calling substations with trunk circuits, an object being to provide simplified and improved circuit arrangements new features of' which will be pointed out more particularly in the following specification and claims.

One of the features of my invention is theprovision of circuit arrangements whereby 'an operator may check the number of the callin substation, after being given by V, the subscriber thereat in making a call. For

instance in automatic systems wherein certain connections` such as toll connections are completed by an operator who desires to know the number of the callin substation unless the operatorV has means or checking up or proving that. the number given is correct the subscriber might give the wrong number. Therefore, l provide means whereby the operator may complete the connection and also has means to connect directly to the terminals of the line of the telephone number given and then by means of a signal determine whether the line number given by the subscriber is or is not the correct number.

ln illustrating my invention I have chosen to embody it in an automatic telcphone system adapted for connection between several exchanges, and include toll circuits for interconnecting the telephone lines of the different exchanges and also a checking circuit controlled by an operator for the purpose already vset forth.

1n the accompanying drawings all parts are shown at normal and parts having like functions are designated by like reference characters except for the exponents.

Figure 1 of the drawings comprising parts l and illustrates circuits for connecting a substation from a so-'called two-wire ex- Speciiication of Letters Patent.

ephone systems,

Patented Dec. 25, 1917.

Serial No. 896,853.

change to a substation in a socalled threei to Fig. 1 by placing part 2 thereof vto the vright of part l, it may be readily followed from the ensuing description thereof. The circuits shown in Fig. 1 part 1. and to the loft of the dotted line in part 2 are preferably associated with the A exchange while the circuits shown to the right of the' dotted line of part 2 are preferably associated with the/B exchange,.althougli as will be, pointed out, the switch circuits of Fig. 1 part 2 may be used in the A exchange.

Referring now more in detail to the apparatus of Fig. l a. substation A is illustrated comprising the ordinary switch hook and receiver. transmitter, induction coil, call bell and condenser, two-wire callin device CD and ring-ing key RK, these al being well understood and no further description thereof being det-ined necessary. A. telephone line-comprisiug a pair of line conductors l--Q connects substation A with a first selector switch B at a central office, alsoterminatiug in terminals 3-4-5 before automatic connector switches in a well known manner.

Selector B is preferably of the well known Strowge'r type and comprises an iinpulsc relay IR, a vertical magnet VM, rotary magnet- RM, private relay PV, release magnet REM, side switches 6, 7, 8, 9, 10, Wipers and cooperating bank contacts, and :i cutoll' relay CO. A slow acting secondary ,relay SR is provided for controlling tliestarting of the seconder selecting movement of the* switch, and a s ow acting release relay RR adapted for controlling the release of thc switch. Both relays SR and RR are so adjusted with relation to the speed of calling device CD that they will not retract their armature responsive to impulses effected by said calling device. Off-normal switch ON is. adapted to moveto its alternate position upon the first primary or verticalstep of the wipers, being restored uponl restoration of s'aid wi ers. The service meter magnet SM is so a, justed that it will not respond to ,current through one of its windings only,

or to current-through vbothof its windings differentially, but will respond'v only to current acting eumulatively through its two windings. a i

Trunk circuit C Vincludes a line relay LR which is adapted to be energized by current over the callln line "upon connection made with saidtrun circuit,rwhereby signals S are displayed to indicate 'that the trunk terminating 1n jacks v 7' has been selected. These multiplyA connected jacks'nj and associated signals Siaredisposed beforeoperators at a switchboard, in which case ajack and associated signal is placed, one Afor each o ra- A reversing relay 4R. 1sadapted' to. reverse the current over thercall-y tors position.

" ing; line for operating service meters and also controlling -su ervisory apparatus as will be more particu arly described. Several other relays are included in this circuit, the

,functions of whichwill be more particularly pointed out'in the description of operation.

. 'Operators cord circuits D are provided $5v Y and linclude an answering supervlsory relay AS and a calling supervisory relay CS these being of the .polarized type. An answering plugAP and calling plug GP are connected by the heavily marked talking conductors havin an interposed and a calling device key DK, key adapted to connect the operators'set O in circuit with the link D'while key DK isA adapted to connecte calling device CD1, in .circuit with 4the calling end of the link. Two supervisory signals SS and SS1 are provide( #being controlled from their respective associated ends of the link D. Relays AS and CS are of comparatively hi h resistance so as not to unduly shunt tie voice currents. y

Out-going trunk circuits 'l are provided for the toll operators, said circuits terminating in second. selector-switches E at the distant exchange, the apparatus to the left of the dotted line in part 2 being located at i the' A exchange while the apparatus to the right of the dotted line is preferably located :1t-.the B exchange. .Trunk circuits Tare,

multiply. connected to jacks 7" before the different signal S1 preferably arranged to be operatedwhile their associated trunk T is busy t0 indicate' operators positions, there being a or each jack, these signals beingsuch busy condition, but so far as some of the features of my invention are concerned other means for indicating a busy trunk may be provided.

Switches E are preferably arranged as eom- 70 bined second selectors and repeater switches, that is the circuit arrangement E is adapted to repeat impulses transmitted front-a call-v ing station to another connectedv switch. 'Switch E comprises an impulse relay -IRv 75 adapted to be-energized over a metallic circuit upon connection made with switch E over trunk T, a reversing relay RV1 for reversin the battery flow over trunk' circuit T, a iil'erential relay DF for controlling o the application of ringin current, an intery rupter or flip-flop relay F adapted togbe nitiall` controlled by aringin :control relay Rd' a second control relay- R for stopping the ap vlic'ation of ringing current'u on' g5 responseV o 'the calledsubstation, a s ow acting release relay RR.1 anda pair of seeondaryrelays: SR?, SR2 which actcon'ointly to cause a secondary circuit change. or the transmission of a seconda or rotary impulse. Relays SR1 and SR are both of the slow acting-typepbeingso adjusted as not ,to retract their armatures when the circuit is interrupted by an im ulse-operation of relay IR1, and relay i 2 being adjusted 95 slightly slower than SR1 so that when their circuit is interrupted SR1 retract's its armature first followed by the retraction of ,the armature of SR.v A suitable number'o'f side 'switches 'are `also 'provided as isl also the 10o usual vvertical magnet VM1, rotar' magnet RM1, releaseA magnet -REM1 an private magnetPV.l 'A

Connector switch F which is lalso ,of the Strowger type, includesa "ertical relay VR, 1&5

rotary relay ROR, vertical magnet VM, rotary magnet RM, release vmagnet REM', private magnet PV, a ringing rela RI, ringing generator RG, an answering ridging relay AB and a calling bridgin relay'll CB together withthe usual side switc arms, off-normal contacts and a busy 'back BB. The subscribers automatic switches in the ,B exchange are of the three-wiretype and l have illustrated a so-called three-.wire sub- 115 station I-I connected by line L1 to'the first selector G at the central ofliee, the switch being of the well known Strowger'type undA a further illustr'ation'thereof is' deemed unnecessary although I have shown cut-off relay COl and one of the side switch arms. Oi course it is to be understood that so far as some of the features of my invention are concerned the subscribers automatic apparatus in exchange B may be of other types 125 than three-wire type. Y

Although l havevreferl'ed toV switches E and F heilig associated with the Biexchange these switches may be used in the A exchange for use in-interconnecting telephone lines 139 thereat and I have shown at second selector E three sets of terminals T1 which may be terminals of first selectors B in which case trunk circuit T may bev disconnected 'from switch'E at contacts 160.

Checking system.

nection, and the toll opera-tor then asking for the number ofthe calling substation and the called substation completes theconnection. It will beV 'apparent that un#A less the toll operator has some' means for ascertaining whether the Inumber given is really the calling substation ,number or not, the calling subscriber could give the wron number and therefore the charge woul be made against the wrong substation. Therefore, I rovide a checking circuitby which the tol operator who is completing theconnection or some other operator, may

extend a. connection to the terminals of the ,telephone'number givenV by the calling s ubscriber and connect a characteristic signal thereto which will be transmitted to the toll operator, or this' other opera-tor, if the number 'ven is correct while if the wrong numberv as been given this signal will not be extended to the operator who will then know that something is wrong.

This checking system comprises preferably automatic switches of the Strowger type controlled by the checking operator` or toll operator which are adapted to-extend connection' to the called terminals of the lines adapted to be checked in the present in-4 stance these switches `being special iirstselectors L and connectors M. Of course.

other selectors may bel included between switches L and M depending on the number of lines served. 4

First selector L comprises apparatus similag1 to first selector B and has an additional pair of wipers 102. 105, connected throughcondensers to the heavily marked conductors, while 'the connector switch M has the usual vertical magnet VM, rotary magnet RM, releascmagnet REM, private relay PV, impulsel relay IR, secondary relay SR, release relay RR, together with side switch contacts and wipers and bank con. tacts. It will be noted that the connector switch has but twol wipers, the conductors connected thereto extending to the extra.

pair of contacts in' the second selector.

switches L whereby the connection when `completed extends over the heavily marked conductor of the first selector to the checking test tone TT which may be a characteristlc signal. 4

The circuits in Fig. 3 shown at A, B, C, D and T represent dlagrammatically a connection extending from a calling substation A to trunk circuit T this being illustrated to show the` manner in which the checking circuit and tone test TT are applied. In Fig. 3 lI have shown an operatorstelephone O1 extending from cord circuit D, this beone is employed.' Y 4 In general the checking system operates as follows:` Assuming a' subscriber at substation A has had a connection extended'to the 'ing for the use of a checking operator when toll operators cord circuit D and .through t0 trunk circuit T, and assuming that the toll operator does her Aown checking, she operates switches L and M to connect to termi` nals of the telephone line whose number was given by the calling subscriber. If the call? ing subscriber has given the correct number, that isi the number of his telephone line, upon the toll operator connecting the test tone TT by 'key'DK1, a characteristic test tone will be transmitted to the terminals of the line connected to and then overv the connection through switches B, C, and D' tothe Voperavtors telephone O whereby the operator knows that the number iven is correct.

Auming now that t e calling subscriber gavean incorrect number, 'that is, not the number of his owntelephone line, vthe operator will extend connectlon through switches L and M to the terminals of this telephone line and upon connecting the test tone TT to the terminals .thereof,`di1e to the fact that this line is not connected back to link circuit D, 'the operator will not receive this test tone and knows that the number given .was

the wrong one.

If it is desired that special checking operators be employed for performing this checking operation duringbusy hours or infact at all times, a circuit may be .extended from cord circuit D to such checking operators telephone set O1 so that this operator may, do her own testing, the conversation between the operators being either over an order wire in the well known manner or they may be situated in close '.proximity to eachother so lthat no order wire need be used.

` Operation, Fig. 1. Having described more in detail the 'apparatus of Fig. 1, an operation of the system in establishing a connection between a calling subscriber at A and a called sub,- scriber at H will now be described.

The subscriber at A upon initiation of a call removes his receiver from its switch hook whereby a circuit for impulse relayv IR isestablished traced from ground through the lao upper winding there-of, normal contact of side switch 6, winding 12 of service meter magnet SM, normal Contact 1,3, liuc conductor 1 substation A, line conductor 2, normal contact 14, normal' side switch Contact 7, and the lower winding of IR to battery causing the operation thereof whereby its alternate contact'l is closed establishing an energizin circuit for release rela RR.

'he subscriber at A desiring a connection which is to be in'ade through an operator, whom we will assume is a toll operator, will operate callin device CD say to cause five operations of t e impulse springs, (assuming the fifth level of contacts is reserved for such service) this resulting in five interruptions of the metallic circuit including relay' IR whereby said relay operates its armature five times. Responsive to the first retraction of the armature of IR, its normal Contact 15 is closed and due to the fact that relay RR 1s a slow relay its armature is maintained attracted and its alternate contact 16 closed whereby a circuit is extended from ground at normal contact 15 through said alternate contact- 16, thewindings of relay SR and vertical ma et VM, and side switch 9 to battery resu ting in the energization of SR which is maintamed energized responsive to the Vfollowing impulses from normal contact 15, thus closing its alternate contact 17 thereby energizing private magnet PV whilel the five said impulses cause five operations of vertical magnet VM whereby wipers 18,` 19, 20 are stepped to the fifth level of contacts 21, 22` 23. After the last operation of IR,

relay RR is of course maintained energized through alternate contact 15 while sec0ndary relay SR retracts its armature inter rupting alternate contacts'll'` whereby private magnet-PV denergizes moving the side -switch 'arms to their middle position. Upon side switch 9 assumin its middle position I; vibratory circuit is c osed through rotary magnet RM whereby the wipers are stepped into enga ement with the first set of contacts ofthe se ected level, the first operation of magnet RM due to a mechanical connection moving the armature of private ma guet .PV

to its attracted position. Therefore if the first encountered set of contacts 21, 23 lead to a busy trunk circuit C, the test ceu tact 21 thereof is grounded so that magnet PV is energized and rotary magnet RM coin tinues to advance the wipers until an idle Set of contacts 21, 22, 23 is reached `whereby the circuit for private magnet PV is inter rupted causing its-denergizatiou whereby the side switch arms are moved into their last position thus interrupting the circuit for rotary magnet RM.

As soon as side switch arms SW7 more into their third position av circuit tor li relay LR of the seized iruni; il' i over a circuit including the all incasso The ener 'zing circuit for LR is traced from ground t rough the'upper winding thereof, normal contact 24, contact 22, wiper 19, side switch 6, winding 12, normal contact 13, line L and substation A, normal contact 14,

-side switch 7, wiper 20, contact 23, normal contact 25 and the lower winding of LR to battery causing its ener 'zation.. Its alternate contact 26 is there ore closed connecting ground over the private or test conductor 28 and through release relay RR'to battery maintaining it energized and its armature attracted. This ground connection of course also holds a circuit through winding 12.1 but magnet SM it will be remembered does not operate unless current is acting cumulat-ively upon both windings. Also responsive to the closing of alternate contact 26 of relay LR a circuit for signal lamps S is established through normal contact 27 and said lamps S to battery lighting said lamps and notifying the operatorsthat a connection is desired with the selected trunk circuit C.

One of the idle operators in response to the si al received inserts the answering plug P of a cord circuit D into a jack j of the selected trunk circuit C whereby a' circuit for cut-o relay C()z is established traced from battery through the winding of CO* and the third contact of jack j and plug AP to ground causing its energization whereby the circuit for lamps S is interrupted at normal contact 27 and ground fromY the third conductor is connected through alternate contact 27 to the private conductor 28 thus maintaining the release relay RR of first selector B energized until the plug AP is again withdrawn.

The operator now closes her listening ke LK thereby connecting her telephone set in circuit with the calling substation to ascertain the wants of the calling subscriber and assuming that connection is desired with telephone No. 234i at the B exchange, the operator. inserts railing `plug CP into the jacl; of an idle treni( ',l" leading to said exchange. Thereafter the operator throws her calling device hay DK to connect calling device CD1 in circuit with trunk circuit T. The operation of DK also closes' alternate contact 29 thereof thereby connecting ground through the sleeve strand 30 of cord circuit D, sleeve strand 31 of link circuit C, alternal-c. Contact 3Q, winding 33 of series relay 34. norn'uil contact 25 and the lower windin 1 of. LR to battery causing an energization o relay whereby i alternate contacts 35 are cli a locking circuit through n., i i ce winding 331 and llt,

conductor 28 to ground thus locking relay 34. The closing of alternate contacts also connects ground from coi'iductorI 28 throu h conductor 36 and alternate contact 5 37, re ay RV to battery causing its energi-l c zation whereby its alternate contacts 24-25 are closed reversing the direction of current Bow over the calling line and thus throu h the winding 12 of service meter'magnet S' 1I mcausing 'an operation of said magnet SM as lits windings are now acting cumulatively. Also responsive to energizati'on or relay 34 its alternate contact 39 is closed thereby sliiinting winding 33 and condenser 40 and l5 excludin Athem from the talking circuit.

"plus direction to ei'ace'l si al SS. 5; The operator having connecte callinv' device C D*.in circuit with trunkv circuit ari energizing circuit fr impulse relay IR* at r@second 'selector E is established traced from vE ground through the' lowerjwinding of difg ',@ferential relay DF, theA lower winding of 1K1, normal contact 42, sleeve contacts of `jack j*"and plug CP, key '.DK'and calling A,devic'e CD, ltip contacts of plug CP and jack j, normal contact 45, the upper wind? 5 ing `of relay IR, and-DF tov batter causing an energization of IR, but relay differential does not-energize to attract its anbpp'oslte,

armature.- Responsivelto the closing of alternate'contact 46 of relay IR* the slow ,j acting relay'RR* is energized' and is now maintained energized until a. release or disconnection is desired.

Upon the operator inserting plug CP in a jack j* a circuit is also established from ground through the third contact of said plug and jack and through lamps S1 to batrery lighting said lamps to indicate that the trunk connected'to the associated jacks is busy. Of course, it is to be understood that .o any well known busytest device for determining lthe condition of trunk T may be provided in place of lamps S* if desired.

The operator now wishing to make connec-tion with telephone No. 234 in the B cx- 5 change first operates calling device CD1 to cause two' interruptions of its impulse springs whereby two operations of impulse relay IR* are effected und upon thc first operation thereof its normal contact 47 is'closcd i musing energixation of secondary relays SR, SR2. These relays' being of thc slow :ii-ling type maintain their armatures ntlrultcd hiring any followingr operations of relai' llt. Rcsponsivll to the tiro operations of relay llt* its ornnil contact tu is closed It' wiF Abe noted that upon insertion ofand 4, operation ,of RV, relay 'AS is. operated in' twice, thereby transmitting two impulses of current through vertical magnet VM* traced from ground through saidnormal contact 46, alternate contact 48, normal contact'49, ,normal contact 50, normal side switch contact 51 normal contact 52 and the winding of VM* to battery causing two operations thereof and stepping wipers 53, 54, 55 to the second level of contacts 56,57, 58 which are the contacts leading to connector switches F in the second hundred group of lines. After the said two operations of IR* its armature remains attracted and' its normal contact 47- interrupted for a long enou h period to allow denergization of SRf foldowed byl SR2 whereby arotary or secondary impulse-` is transmitted from ground at normal contact 59, alternate contact 60, normal sideswitch contact 61 and the winding of PV* to'bat-'f' tery causing an operation Vthereof whereby the side switch arms are stepped intotheir 4 middle position.4 U on side 'switch arm'l 62 moving to itsmidd circuit f or rotarylma' etRM* `is'es'tirblish the firstoperationr't 'erect-"ste ping wipers 53, 54, 55 into len'gagenient wi the firstset eposition a vibratoeizy .t 7.

of contacts 56, 57, 58, and due tothe closing l of its alternate contaetan enerfirizngcir-` @uit for private magnet rvx iasaaished so that if the first en'oiint'ered's'et of. contacts r lead to a4 magnet PV* circuit includinltestwiper 53 thisnmaintain# ing-'circuit for Y* co'ntiniii'n until-wipb'- 53 en ages lanidle or ung'roun ed contact 56 Where y side switch' arms' into their third or last pobusy-connector switch F private for rotary magnet RM*. Ypon side switch arm 64 moving to its last position' 'ground is connected through, wiper' 53 to multiple 'contacts 56 rendering connector switch `F bus rl'he operator now o eratescalling device (JD to el'ectthree interruptions of. the metallic` circuit including impulse'relay V11,1* whereby said causing energization of the slow actin secondary relays SR, SR, and maintaining them energized until cessationof said operations .as before, while three impulses of current are transmitted throeugh th'e' vertical relay VR of switch F trac from ground' at normal contact 46 of relay 1K1, alternate contact 48, normal contacts 49, 50, third'con'- tact of side switch 51, wiper 54, contact 57, Vrelay VR and the upper winding of relay AB tobat'tery causing three operations of is maintained energized "over 'a i magnet PV*'.restores moving the 'siton and thereby interi-u ting the circuit relais operated three times said relays VR, AB. Res onsive to the (N3, noi-mal side switch contact 67 and theI ii-hiding o f VM to batteryV causing three .,tact`60, third side switch contact 61, 'wiper operations thereof and effecting three vertical steps of wipers 68, 69, 70 to select the third level of contacts 71, 72, 73 which is the level includin the terminals of the called line L1 of su tation H.

After the said three operations of IR, relays SRl and SR denergize in thesame order as before whereby fa secondary or frotary impulse is transmitted from ground through normal contact 59, alternate con- "and-.- maintained "energized -as before and -fou'r impulses ofy'cuirent are.transm tted "ffroinf undat normal-'contact 46 ofA IB'.1 over?, e' previously described path causing foiir operationssfof vertical relaygVR wherecurrentthrough'. rotary magnet Mand Steppin-gni ers as, 69, 7o toahefea'rthset Q ofcontacts'. l, 72, 73 in the'sclected level which arethe terminal contacts ofthe called line.' Thereafter relays SB,SR denergize 'as before' -transmitting a rotary impulse throughrelays ROR and AB causing a single o eration of said relays.' Responsive to the c osing of alternate contact 76A of ROR, private'relay PVz is Ioperated as before thereb stepping the side switch arms into their ast osition whereby assuming the called line is idle, ground is connected from the third contact of side switch arm 77 to wiper 68 and contacts 71 and to cut-off relay vCOl to battery causing its energization and removin the substation control of first selector G. he closing of side switch arms 78 und 79 closes the heavily marked talkin conductors 0f switchvF whereby the called bridging relay CB is connected in bridge of the called line but due to the condenser :it substation H it is not operated until the called subscriber responds.

The operator now :ictuates rin ing key RK1 thus groundinv the tip confuctor of trunk circuit T anv causing an increased flow of current through the upper winding of differential relay DF whereby its armature is attracted and thuszalternate contact 8O is closed establishing a circuit for ringing control relay RC traced through the winding thereof to ground at the third con- ,the lower heavily marked rota tact of side switch G2. The relay RC is thus energized, its ,alternate contact 81 bein closed whereby a locking circuit for itscl -is established and due to the closing of its alternate contact 82 a circuit for interruptor relay 4FF is established from battery through said alternatecontact 82, the winding; of

eel

FF, normal contact83 and interrupterw I to' ground, the interruptions of said circuit by interi-u ter I causing corresponding 'op. eration? OF F whereby alternate contact 56 is periodically -closed thus establishing se riodical-- ener izing circuits for relays R and AB of Ig, traced from said'ground at alternate'contact 50, third side switch conin 4corresponding nergizations of R1 wherebyringi'ng current from ringing generator 'RG-is' connected through alternate contacts 86,87 in-{bi'idg'e an o ration o t 1A t'er thev operator liasdepressed ringing ke l) whereby 'polarized rela S' is edf in brid 'j'ofthe trunk circuit T but said :relnyCS is so' connected that current from buttery Ythrough 'relays DF and TR?. is inY a direction-not`-adapted toelose its alternate contact 88,- but u n response of the called subscriber 'as wil be seen, the current flow through saidfmagnet CS is reversed to cause effacement o f signal SS?.

The subscriber H in response tothe operation of thecall si 'al removes his receiver from its switch ook wh reb {RK- ,fshejrestores callin 'device keyV of the calledt line causin lie call bell at substation 'ion a circuit through relayv CB is establis ed rom ground at the thirdv contact of side s witch 77 of connector F, 'the lower winding of CB, norA mal contact 87, third Contact 79, wier 70, contact 73, line L and substation contact 72, wiper 69, third contact 78, conductor 89 and the upper winding of rela CB to battery at normal contact 84. Thiscircuit results in the energization of relay OB (to ctl'ect operation of RV of E) whereby its alternate contact '75 is closed thereby con# nccting ground from third side switch contact 7 through said alternate contact 75, lower winding of A'B, relay ROR, back over through alternate contact 90 which has been closed, reversing relay RV along the upper heavily marked vertical conductor through vertical relay VR and the upper winding of AB to battery this current How being sufh cient to pcrnte reverse relay RVl but not sufiicient to operate relays VR, AB and ROR.

conductor,

iro

The operation of RV1 effects the closing'l -contact 62 causing the closure of locking o itact 92 of relay DR and due to the'interruption of its normal contact 83 further op- V(iti eration of interrupter relay FF is prevented thus preventing any further application of ringing current to the called line.

Also, responsive to the operation of BVl -its alternate contacts 42, 45 are closed thereby effecting the said reverse of current through the polarized relay CS causing its restoration and interruption ot its alternate contact 88 thereby eifacing signal SS1V and notifying the operator that the called subscriber has responded.

Thus it will be seen that the two substations A and H are connected for conversation the .talkin circuit being traced over the heavily, mar ed conductors.

checking mwa,

Having described the operation of the system in establishing a .connection between a calling and a called substation, the method of checking the number of the called substation will now be described, reference being made to Fig. 3 of the drawing. As previously stated the checking operation may be performed either by the toll operator who establishes the connection between the substations or by a checking operator, but for the present we will assume that thev toll operator or the operator who is establishing the connection performs the checking operation.

When the toll operator answers the call to ascertain the Wants of the calling subscriber she also requests the number of the calling substation, which in the case of toll service is used to make the toll charge, as is wel] understood. In Fig. 3 I have indicated by the diagrammatic circuits A", B, C, D, T, a connection established from calling substation A to called substation H but have indicated only enou h of the circuit connection to show theinetiod of operating the checkin system.'

avin ascertained thenumber of the calling telep one' line L, which we will assume is No. 345, the operator throws a calling device key DK1 to connect a calling device CDs in circuit with a selector switch L, this connection resulting in the energiaation of impulse reiay'lRs over the inetallic'circuit including the contacts of said device CD3 and responsive to energization of IR3 its alternate contact 151 is closed causin4 the energization of release relay RRa'whieh is now maintained energized until a release of the switch is desired. The operator then actuatcs calling device CD3 to effect three iii-1 terruptions of the metallic circuit including IRS whereby said relay is operated three times effecting three operations of vertical magnet VMa and three vertical steps of the wipers in a manner which will be well understood from the previous description of first selector B, secondary relayr SR also being energized responsive to these three operations to effect the energization of private magnet PV".

busy second selector M, relay PVa is maintained energized and the magnet RM3 continues to step the wipers until an idle set ot contacts is reached whereby the maintaining circuit for PV3 is interrupted causing it to denergizc and move the sidey switch arms into their third position thus preventing .any further operations of RM"s and extending. the metallic circuit includiii calling device CD"l over the heavily mar Yed conductors and through the impulse relay IR* t battery causing its energization.

After thc said three opera- 4tions of IRa, relay SRa dcnergizes allowing Closing of alternate Contact 111 of relay IR4 connects ground to the multiple contacts 106l preventing any other switch L from connecting to switch M, this connection also being adapted to maintain relay RRa energized. Also upon closin of alternate contact 111, release relay 15K* is energized.

The operator now actuates callin device GDa to effect four operatioiis of re ay IR* wherebyr four impulses are transmitted through SR, VM* Vand vertical magnet VM is operated four times to cause four vertical steps of wipers 112, 113 wliile'secondary relay SR* due to the closing of its alternate contact 114 causes private magnet PV* to step side switch arm 115l into its middle position after the said four opera-tions. The operator again actuates callin device CD this time effecting five operations of relay IR* resulting in five operations of-rotary magnet RM* and stepping wipers 112, 113-.

no existingl connections will beA interfered` ivate magnet lV steps the-Si e switch arm into its third position due tothe circuit` through alternate contact 114.

Thus, it will bc seen thzit if the calling gull.. After the last saidfiye Vdei'atio'nssubscriber. has given the correct number a circuit will be established from calling device key DK1 over the heavily marked conductors to the terminals of the calling line and then over circuits D, C, D, to operators circuit O so that upon the operator throwing her key DK1 to connect test tone device TT in circuit, a signal will be transmitted over the said circuit including switches L, M, and circuits C, D, to operators telephone set O where she receives the signalaiid is thus informed that the subscriber has given the correctl number.

This test tone is traced from induction coil `118 of apparatus TT along the upper heavily marked vertical conductor, condenser 119, wiper 102, contact 107, tlie upper heavily marked conductor of M including normal contact 115, wiper 112 and contact 4, vertical conductor of first selector B, ti-p conductor of trunk circuit C, the tip conductor of cord circuit I), and through listening key contacts LK and operators set O returning over the sleeve-conductor'ofv cord circuit D and trunk circuit C, the rotary conductor of.

A first selector B, contact 5 and wiper 113, nor

i connecte mal contact 116, contact 110 and wiper 1051` condenser120, rotary conductor of L to in,

It will be apparent that if the 'calling subscriber gave some other number than his own, that wipers 112, 113 would have been to 'terminals 4, 5 of some .line which is not connected back through cord circuit D', so that when theoperator connected the test tone TT to the checking circuit the Asignal would not be .received and she would know that something was Wrong.

.A If it is desired to have some other' oper-` ator than the toll operator to do the checking such other operator may be infomed v either directly or through an order wire of a calling subscribers number and she may then'` operate the checking circuit in a manner as before and then connect her telephone set O1 by means of the listenin key LK1 and thus determine whether t e number 'given was correct or not.

After the checking operation has been performed, by restoring key DK1 to its normal position the circuit for ,relay IR* is interrupted causing its restoration, and due to the interruption of its alternate contact 11,1

' release relays `RR3 and RR* are restored, the

restoration of rela RR3 closing its normal contact 16 where y a circuit for release magnet REM"i is establishedfrom ground through normal contacts 151, 161', the winding of REMs through olf-normal s'witcli ON3 to battery causing the energization'of the release magnet whereby switch L is restored in a well known manner.

Upon restoration of RR4, .its normal con-4 tact 1111 is closed wherebyan energizing circuit for release magnet REM'is estabflow. through .polarized relay tion wherebya circuit is niomentarillzy 9 receivers to their respective switch hooks, the restoration of the receiver at A causing an interruption of the circuit through relay LR which restores to normal and due to the interruption of its alternate contact 37 relay RV restores thereby reversin the current to close its alternate contact 81 and operate supervisor. si a1 SS,- lindicating to the S causing it operator t at t e calling subscriber hasrestored his receiver. Although relay LR has restored interruptingits alternate contact 32S' s,

battery for rela AS is V impedance coil l() and a though alternate contact 26 of relay LR is interrupted relay RR`of switch B, cut-olf relay C()2 and series relay 34are'st1ll maintained energized by the ground through the third contact plu APvso that switch B Vis not restored unti lthe plug is withdrawn from the jack as will be described.

. The restoration of the receiver at substaA tion H interrupts the circuit for bridging rovided through A lay CB whereb .it is restored and due tothe ,l

interruption o Vits'alternate contact 75, the

circuit for reversing relay RV1 of switchl Ef is interrupted causingits restoration whereby the flow of current through calling Superf visory relay CS isreversed causing it to c its alternate contact ,88 'and operate supervisory :signal SSl indicating to the. o rator that the calledvs'ubscriber has replace his re; ceiver. The release of switches E and F withdrawn from the trunkjack 1.

. The operator in response tot e operation of signals SS, SS, withdraws plugs AP and CP roin their respective jacks, the withdrawal of plug AP causing the interruption of the circuit for cut-olf relay CO', relay 34 and release relay RR of switch B, resulting in their restoration. The restoration of RR results in the closure of the circuit through release magnet REM traced from ground through normal contacts 15, 16, magnet REM and olfnormal contact ON to batter does not occur until the calling 'CP is 'iio resulting in the ,release of switch B-in awe I known manner.

through relays SR1, SR* of switch traced closed -Thus switch Band trunk 4circuit C having been'restored they are available for use inYestablishing-othercon-v contact 481 and the windin of relays SR1,

aasasoo from ground at normal contact 47, alternate SR to battery, this circuit eing interrupted upon the immediately following restoration of relay RR1. Relay SR1 being quicker to restore than SR2, a ground is momentarily connected to the rotary conductor of switch E resultin in the energization of the rotary relay ROR of connector F over the previously described path while an impulse of current is also transmitted over the vertical conductor through the/vertical relay VR of connector F traced from ground at normal contact 46 of relay IRI, normalcontacts 48, 591",4alternate' contact 60, vertical conductor to wiper 54, conta-ct 57, relay VR and the upper winding of AB to batte re sulting in the energization of VR and A y Responsive to the simultaneous energization of relays VR andROR, their contacts 125 are closed establishing a circuit for release magnet REM2 traced from ound through said contacts 125 the win of REM to battery at alternate contact 84 resulting in the energization of the release magnet and the restoration of switch F in a well known manner. It might be added that due to the closing of alternate contact 7 6 of ROR, private magnet PV2 is energized and by its contact 66 interrupts the circuit for ringin relay RI preventing any false operation t ereof. The restoration of side switch arm 7 7 interrupts the circuit for cutoff relay CO1 restoring it and therefore the substation control of switch G.

Referring now to the restoration of selector E, after all of the relays IR,'RR1, SR1 and SR are restored an energizing circuit fdr release magnet REI/I1 l:is 'established traced from ground at normal contact 46 of for release magnet REM1 is established contact ON1 and the windin of REM1 to battery causing its energzatlon and therestoration of switch E. Upon restoration of side switch arm 62 the circuit for ringing control relay RC is interrupted causing its restoration while the restoration of arm 62 also interrupts the locking circuit for disconnect relay DR allowing it to restore. Switch E and trunk circuit T having been rendered idle are again available for further use in establishing other connections.

Called Zine busy.

ln the foregoing description it will be remembered that it was assumed that the called line was idle but we will now assume that the line L1 of substation H was busy upon connection made therewith by connector switch F, in which case switch F is automatically restored and a busy signal transmitted.

Responsive to the last rotar impulse whereby relays ROR, AB and P z"were energized, an energizing circuit for release magnet REMa is established traced from the grounded private or test terminal 71, wiper 68, middle contact of side switch arm 77, alternate contact 661 and the winding of release magnet REM2 to battery at alternate contact 84. The resulting energization of magnet REM2 is e'ective to restore switch *F in a well known manner, but the operator l at D not aware as yet that'the called for line lis busy, operates her ringing key RK1 in the usual manner thereby operating vertical relay VR and relay AB as before whereby connector switch F is stepped off-normal by the resulting operation of magnet VM. Oif- `normal contact 0N2 is thereby closed connecting busy back BB to the rotary talking conductor and thus a characteristic busy signa-l is transmitted from BB along the lower heavily marked conductor out over the calling line and substation A returning over the upper heavily marked conductor and through the upper windin of line relay LR of trunk circult C throughattery to groun The calling subscriber in response to this signal replaces her receiver upon its switch hook thereby operatin supervisory signal SS in a manner as be ore described, while supervisory signal SS1 havin` remained-operated, the operator at D withdraws plugs AP and CP from their respective jacks effecting the restoration of switch B and trunk circuit C as before while switches E and F are also restored in a manner as before described.

Branc/i. ewa/Lange w1/ml: J.

Fig. 2 illustrates a trunk circuit ada te/d for interconnecting branch exchange ines with a toll board preferably located at the A exchange and therefore l have preferably arranged the trunk circuit J as a two-wire circuit the apparatus to the left of the dotted line being associated with the branch exchange while the apparatus to the right of the dottedV line is located at the A exchange.

Substations and first selectors similar' to those of the A exchange may be used at the branch exchange and therefore trunk circuit J is adapted for use with such apparatus. Relays of trunk circuit J and relays of trunk circuit C having similar functions have similar reference characters and comprise a line relay LR3 adapted to be energized by current over the callingline responsive to connection made with terminals 211, 221., 231

whereby a circuit is closed through line reusualrnanneru that is by inserting a plug AP- ofthe c upon withdrawal of a connecting plug from jacks j.

. In establishing a connection from the calling substation in a branch exchange toan operator-S position in the A lexchange and assuming that the calling substation is similarto A while its first selector is vlike B, the connection to terminals 211, 221, 23l of an idle. trunk J is established in a manner as before described. Upon connection. made with said terminals, relay LR is energized by current flowing through its winding and over the Qcalling line whereby its alternate contact 261 is energized' to hold release relay RR at first selector Benergized. `An energizing circuit'for relay LR.4 is also established upon such connection,-being traced from battery through the lower winding of LR3 out over the'calling line returning over the tip 'strand of trunk circuit J, normal contact 150 and the upper winding of LR* to ground causing its energization whereby its alternate contact 1 51 is closed establishing a. circuit through normal contact 152 'and signal lamps S3 to battery effecting their illumination.

' An idler'onc of the operators before whom 'acks '3 are located answers the lcall inthe J in a jack js., /A series circuit for relays LR, CO;1 is established from ground through the third contact of plug AP 'and-jack j and then th'roughthe windings of relays CO3 and LR* to battery energizing CO3 and maintainingu relay LR. energized until withdrawal of` the plug. vDue to the interru tion of contactll52 of CO3, signals S3 are e Aaced. After ascertaining the number of thewanted line inthe usual manner the operator pressesA her calling'fdevice key DK thereby establishing an :energizingcircuit ,for relay 341-. through its upper winding 33.?. similar to that of circuit C, whereby saidrelay 341 isv energized closing a locking `'circuit for itself through Aits alternate contact. 351 at normal contact 154. Due. to the grounding of conductor 155 a circuit is established.` through alternate contact 1 56 andthe winding'of 'RVa to'battery causing the energizetion of RV3 and reversing the current flow over thel calling line to operate its service met-er magnet as before'described.

The ofileration of extending the connection a ling substation to that of a called substation ina distant exchange is similar to thatv before described. After theu` subscribers have finishedV conversation they replace their receivers upon their respective switch hooks, the act of the called subscriber operating the polarized relay CS and lighting signal SS1 as before described while the act of the calling subscriber at A restores relay LR thereby reversing the current fiow through polarized relay AS thus lighting signal SS as before, while the `'replacingof circuits of Fig.v 3 for this purpose,

erably placing' the switches as L and in i while the calling de to ground it is to be understood that relay RR3 is ad-v justed not to respond to this current How through relay AS, relay AS being of a compa ratively h1ghresistance. The operator in responseto thedisconnect signals withdraws the connecting plu from their respective jacks whereby switc les E and F are restored as before described.

The release caused by the withdrawal o f plug AP in this case is-diti'erent than in connection with trunk circuit C. Upon withdrawal of said plug AP the circuit for relays CO? and LR* is interrupted at the A third contact of the jack, and. relay LR* being a quick acting relay restores its armature before the restoratlon of the armature of the slow acting relay CO so that a grounded impulse is transmitted 'over the sleeve conductor tracedr from normal contact- 151 of LR, alternate contact'158 over the i sleeve conductor and normal contact 321 and then through the winding of RRato battery causing the energization thereof and theinterruption of its normal contact 154. There- .ii-ore, the holding circuit vfor relays 341, and RR of switch 'B is interrupted allowing.

these relays to restore whereby switch B is restored in a manner as before' described and trunk circuit J and switclr B havin restored are available for use -in establi other connections. I L

As to checking the number of calling lines in the branch exchange, I preferably use'the refthe branch exchange, vice CD2 key DK1 and'test apparatus TT are assoclated with the exchange-where the operator is located, The operation of the checking system with this arrangement is ofv course the same as before described.

f Local automatic comiectom.

VIn the previous description I* have referred to connections between substations located 1n `.different exchanges but for local been shjng work in interconnecting telephones in the A I exchange and branch exchanges bysubscribers automatic apparatus, any' of the well known systems adapted for use with substation's as A may be used but I have provided second selector E with additional -termihals T1 so that said switch E'may be used as a second selector and switch F as a connector 1n sa-ld A exchange and branch exchanges. Should second selector E be -used for such'local work, the automatic terminals 212, 22, 23 are used and the trunk izo of release relay RR1 switch B to pick circuit T may be disconnected` at connections 160.

Should the subscriber at A for instance desire a connection with a local telephone line, calling device CD is operated to cause out a second 'selector E'of the proper up and upon connection bein made with terminals 21, 22, 232 of the switch E, impulse relayl IR1 will'be enerzed by current over the calling line in this instance wherefbefore it will be rememberedthat this rel'ay IRF was energizedby current flowing through polarized relay CS of cord circuit D. Responsive to IR1, RR1 isenergized as before closing its alternate contact 161 and connectin ground to private or test contacts 212 t us 'maintainin switch E busy and irelay RR of first se ector B energized. l

Thereafter the subscriber operates his dial according to the followin digits. of the called substation number w ereby relay IR1 is interrupted as Where it was interrupted by the operators calling device CD1 thus effecting a'noperation'of switch E and thereafter a switch Eto connect to thecalled line as before. The subscriber then operates his rin 'ng key lay F of switch'fE and'causing the applicae called subscriber reversing relay RY* o switch' E is operated reversing thecurrent flow' over the calling line and tl'ius'actuating service meter SM in a manner-"ajs'previously described. I l. After the subscribers have finished conversation they will replace their receivers upon theirv respective switch hooks wherebyl the replacing of receiver at H restores ,relay CB as before thereby restoring reversing relay RV. Responsiveto the replacing of the receiver at substation `Arelay IR1 of second selector 'E is restored effecting restoration of switches E and F in a manner as previouslyldescribed. Due to -the restoration of switch E ground is removed from test contacts 21' thus causing restoration'of relay RR and service meter magnet -SM causin the restoration of switch B as before descri ed. All of the switches and lines having been restored they are available for use inV establishing other connections. `4 Although I have illustrated substatipn as a well known form of three-wire automatic substation and referred to thev subscribers automatic apparatus in the B exchange as being of the three-wire type, I do vnot desire to be limited to the use of such a system b'ut havechosen this particularsys- `tion of ringingfc rent to the called. line. U on response 'ofutg tem to illustrate an embodiment of my invention While ,I have shown a number of batl teries itis to be understood that those bat- RK unbalancng diierential re' teries associated with the apparatus in anyJ one exchange may be all one and the same.

It will be apparent that many changes y and modificationso the system 1n my application may be readily Vmade and therefore I do not' desire4 to be limited to the -exact structure as shown and described buty aim to cover all such 'changes and modifications as come within the spirit and scope of the ap Inded claims. I 'y y ably connecting said lines and link circuits responsive to calls over said lines, connec- Y the .terminals of. a callwhile .connection exists tively connecting to ing one of said lines tion terminals for said lines, andvoperator controlled automatic switches -or opera between said calling line and one 'of said movedA at the calling substation.

2. A telephone system comprising telephone lines, operator controlled link circuits, automatic. switches for interchangeably connecting said lines and link circuits responsiveV to callsr over said lines,-connec tion terminals for said lines, operator controlled automatic switches for connecting to .link circuits, and .while the receiver is resaid terminals of a calling line, and means for transmitting a characteristic signal over said automatic switches and terminals to a connected operators link circuit.

3. A telephone system including' a telephone line, operator controlled link circuits, an automatic switch for connecting said line with one of said link circuits responsive to l a call over -said line, V.connection terminals for said line, operator controlled automatic switches for connecting to said terminals ofy a calling line, and means for transmitting a characteristic. signal over the established 'circuit including said .automatic switches and Vthe operators link circuit.

phone line, operator controlled link circuits, an automatic switch for connecting said line with one of said link circuits responsive to 4. A telephone system includinga tele-- by the operator for establishing a conversaing for extending a calling line to an idle tional circuit over such a connection whereby link circuit, operator controlled automatic she may learn the num-ber of the calling teleswitches for connecting to the terminals of v phone line from the calling subscriber, and a line which is calling, and means for .trans- 5 means controlled by the operator for-.ascermitting a characteristic signal over said au- 7g tainingwhether the telephone number given tomatic switches and terminals to a conby the calling subscriber isv the number of nected operator-s link circuit. the calling line. y12. A telephone systeri1.comprisingtele 6. A telephone system including -a telei phone lines, a central'oice operators switch- 19 phone line, operator controlled link circuits, ff board, operator controlled link circuits there- '75 an automatic switch for connecting said at, switches responsive to'calls over said lines line with an idle one of said link circuits for interchangeably connecting said lines responsive to a call over said line, means and link circuits, called line connection terfor establishing a conversational circuit beminals for said lines, and electromagnetic y tween said calling line and link circuit switches controlled by an operator at the 30 whereby lthe operatormay learn the numcentral 'ollicc switchboard for connecting to o line corresponding to the number `given by 13.' A telephone system comprising telef 35 the calling subscriber, and means for dephone lines, called line connection terminals termining whether the tele hone line con for said lines, a central oliice operators lnected with is the'calling te e hone line. switchboard, operator controlled link cir- 7. A telephone system inc udingl av telel cuits thereat, switches responsive to calls phone line, operator controlled lin'k circuits, dver said lines for interchangeabl 'connect- 9o an automatic switch for connecting said line ing said llilies and link circuits, e ectromagwith an idle 'one off said link circuits' renectic switches controlled by an operator at sponsive to a call over said line, means .for the central olice switchboard for extendin establishing a conve tional circuit between a link circuit to the called line terminals 0% 3g said .calling line andliiik circuit whereby the a-wanted line, and electromagnetic switches 95 operator may learn the number of the call;y controlled by an operator at the central oflice ing line `from the calling subscriber, means, switchboard for connecting to the called line controlled by the operator for connecting to terminals of the calling line that is connected the telephone line corresponding to the numto the said link circuit. ber given b the calling subscriber, and '14. A telephone system comprising tele- 10o means for etermining whether' the telephone lines, called lineconnection terminals phone line connected ,with is `the calling for said lines, a entral olice operators telephone line. v switchboard, operator controlled link cir- 8. A telephone system comprising telecuits thereat, switches responsive 'to calls 40 phone lines and-.means controlled by an op- -over said lines for interchangeabl connect- 105 eratorv including operator controlled autoing-said lines and link circuits, e ectromagmaticswitches for determining the number netic switches controlled b an operator at y line; the-centraloice switchboard for extending 9. telep one system comprisin telea link circuit to the-called line terminals of phone lines, operator controlled link circuits, a wanted line, electromagnetic switches con- 11o switches for interchangeably connecting said trolled zby an operator at the central ollice lines and link circuits responsive to calls switchboard for connectin to the called line over said lines, connection terminals for said terminals of the calling line, and means for lines, and operator controlled electromagtransmitting a characteristic signal through netic switches for operatively connecting to the last said switches to said called line ter- 115 the terminals of a line that is calling and is minals and through the first said switches to connected to one of said link circuits. an operators link circuit. i g

1Q. A telephone system comprising tele- 15. A telephone system including atel'ephone lines, link circuits for extending said phone line, central office operators switchtelephone lines, switches for interchangeably board, an operators link circuit, means for 12o connecting said lines and link circuits con- 'connecting said telephone line`to said link trolled over'said lines when calling, concircuit, an'operator controlled electromageratively connecting to the terminals of a means for transmitting an audible tone over 125 line which is calling and is connected to an said switch to the operators set' associated idle one of said link circuits. with said link circuit. A

Al1. A telephone system comprising tele- 16. A telephone system including a telephone lines, operator controlled link circuits, phone line, a central oilice switchboard, a switches controlled over said lines when calllink circuit' at said switchboard, electromag- 13 0 netically controlled means for connecting said line to said link circuit, a tone device, and operator controlled electroma etic means' for connection tosaid line where y an audible tone from `Said device may be coilnected to said link circuit at the will of the operator.

Signed by me at San Francisco, county of San Francisco and State of California, in the presence of two witnesses. y GERALD DEAKIN.

Witnesses:

PAULINE J. GLAUCH, E; A. MCCANN. 

